.body{
    display: flex;
    flex-direction: column;
    justify-content: space-between;
}

/* 头部视频 */
    header{
        width: 100%;
        height: 340px;
        background-color: #000;
        color: #fff;
    }
    header span.iconfont{
       font-size: 30px;
       position: relative;
       top: 10px;
       left: 10px;
    }